Electric arc lamp



y 24, Y A. RUTTENAUER El AL 1,967,906

ELECTRIC A'Rc LAMP Filed April 26, 1952 fZQ'Z ENTUR 5 ALFRE'E RU? TE'NAUER QT TE FRI?" ZE *2 fiEIF-i A? TURNEY Patented July 24, 1934 warren s'mrss ELECTRIC ARC LAW Alfred Riittenauer, Berlin-Charlottenburg, and

Otto Fritze, Berlin, Germany, assignors toGeneral Electric Compan York y, a corporation of New Application April 26, 1932, Serial No. 607,616

- In Germany May 7, 1931 4 Claims.

Our invention relates to electric arc lamps comprising refractory metal electrodes sealed in a transparent or translucent bulb or other envelope containing an inert gas.

When used as a source of ultra-violet rays, a globule 'of mercury is placed in the bulb and a filament is placed across the arc gap in multiple therewith to facilitate the starting bf the arc. One of the objects of our invention is the provision of means whereby the body of mercury is protected from excessive heating.

A feature of our invention is the interposition of a screen or reflector between the arc and the body of mercury which will protect the saidmercury from excessive heating, .particularly when the lamp is used in a vertical position. A greater amount of ultra-violet rays is radiated when the lamp is used vertically than when it is tilted due to the fact that the heat radiation from the arc is greatest along the vertical axis of the lamp. However, with the screen or reflector disposed below the arc, the radiations from the lamp are more nearly uniform when said lamp is burned in various positions. The screen also serves to intercept particles of dust emanating from the electrodes and prevents their deposition on the walls of the bulb. I

Other features and advantages of our invention will appear from the following description of species thereof.

In the drawing Fig. 1 is an elevation of a lamp comprising our invention; and Fig. 2 is a partial elevation of a modification thereof.

Referring to Fig. 1, the lamp comprises a base and bulb 11 made of quartz or a glass transparent to ultra-violet rays such as boro-silicate glass, filled with an inert gas such as argon or nitrogen. A pair of electrodes 12 comprising blocks or spheres of a highly refractory metal such as tungsten are disposed on the ends of support wires 13 which are mounted on leading-in wires 14 sealed in a stem press 15. A filament 16 which serves to ionize the arc gap is hung in loops 1'? in the support wires 13 to provide high con- 45 tact resistances so that the arc will strike across 'the electrodes rather than across the filament.

A screen 18 of a highly refractory metal such as inolybdenum is disposed below the electrodes 12 and filament 16 and is mounted on the ends of 50 wires 19, the opposite ends of which are sealed into a glass bead 20. Said glass bead 20 is supported by wires 21 sealed therein and mounted on the leading-in wires 14. The wires 19 are provided with loops 22 for the additional support of the filament 16. A globule of mercury 23 is located in the bulb 11.

In Fig. 2, the screen 18 of Fig. 1 is replaced with a reflector 24 comprising a substantially hemispherical cup of a highly refractory metal such 60 as molybdenum or tungsten. The inner surface of said reflector 24 may be polished so that the heat radiations of the arc and the reflector itself, which comes to a red heat, are directed toward a reflector (not shown) used with the lamp. The heat rays are then directed along with the ultraviolet rays in a desired direction.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. An electric arc lamp comprising a bulb, a pair of electrodes disposed in said bulb on opposite sides of the axis thereof so that the arc gap therebetween extends transversely of said axis, a quantity of vaporizable metal in said bulb, and a re fractory screen disposed in the said axis of said bulb between the said are gap and the lower end of the bulb so as to be in the path of rays directed from said arc gap along the axis of said bulb toward said .lower end thereof.

2. An electric arc lamp comprising a bulb, a pair of leading-in wires sealedin the upper end of said bulb and extending into said bulb, a pair of electrodes mounted on the inner ends of said leading-in wires on opposite sides of the axis of said bulb so that the arc gap therebetween extends transversely of said axis, a quantity of vaporizable metal in said bulb, and a refractory screen mounted on said lead wires and disposed in the said axis of said bulb between the said are gap and the lower end of the bulb so as to be in the path of rays directed from said are gap along the axis of said bulb toward said lower end thereof.

3. An electric arc lamp comprising a bulb,v a pair of electrodes disposed in said bulb on opposite sides of the axis thereof so that the arc gap therebetween extends transversely of said axis, a quantity of vaporizable metal in said bulb, and a reflecting screen comprising a refractory cup concave toward said electrodes and disposed in the said axis of said bulb between the said arc gap and the lower end of the bulb so as to be in the path of rays directed from said are gap along the axis of said bulb toward said lower end thereof.

4. An electric arc lamp comprising a bulb,- a. pair of leading-in wires sealed in the upper end of said bulb and extending into said bulb, a pair of electrodes mounted on the inner ends of said leading-in wires'on opposite sides of the axis of said bulb so that the arc gap therebetween extends transversely of said axis, a quantity of vaporizable metal in said bulb, and a reflecting screen comprising a refractory cup concave toward said electrodes and mounted on said lead wires and disposed in the said axis of said bulb between the said arc gap and the lower end of the bulb so as to be in the path of rays directed from said are gap along the axis of said bulb toward said lower end thereof. H

ALFRED RUTTENAUER. OTTO FRITZE. 

